If they are looking to improve the focusing speed with a integrated grip I also welcome that, even with a little extra expense.

I really believe that this focussing speed with integrated grip thing is a nonsense. There is simply no way that an integrated grip would affect focus speed in reality. All the top-end Canon lenses use ultrasonic motors. These are not like normal electric motors where the higher voltage you feed them, the faster they go. The speed depends on the frequency and phasing of the drive signals, and that is generated by the lens microcontroller from a quartz frequency source, it won't change with supply voltage. The only way that the grip would allow faster focus is if the firmware was deliberately slowing down the focus to preserve battery power. That is possible, it might be a bad thing if the camera gets a reputation for low battery life. That's what Nikon is doing - the speed restrictions without grip are entirely firmware. Canon has thankfully been free of that kind of silly marketing ploy, I hope that they don't start now.